Header is not showing on every pdf page

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I am using follwing function to convert gridview in to pdf ..It does well but it adds header on only first page.. How to add header on every pdf page.. please give me the solution for this ..!!
Note : i musig itextsharp dll for this..
Is their any other solution for this
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protected void btnExportPDF_Click(object sender, EventArgs e)
    {
      Response.ContentType = "application/pdf";// Gets or sets the HTTP MIME type of the output stream.
      Response.AddHeader("content-disposition", "attachment;filename=GridViewExport.pdf");
      Response.Cache.SetCacheability(HttpCacheability.NoCache);  // set no cache
      StringWriter sw = new StringWriter();
      //we declare a new StringWriter—which always has an internal
  & ...